This invention relates to a position sensor device (which may also serve as a position-to-speed converter device) for use with an elevator car.
Moving members such as elevator cars are adapted to move along a path of movement having a finite length and accordingly it is a common practice to limit the speed thereof at either end of the path of movement in order to ensure that they stop at the ends of the path of movement. In elevator systems, therefore, it has been already proposed to sense the actual position of the elevator car and compare a command speed corresponding to the sensed position of the car determined by an output from a position-to-speed converter with the actual speed of the car thereby to maintain control of the car. Conventional position-to-speed converters, however, have been disadvantageous in that the position of the elevator car is sometimes erroneously sensed due to the horizontal movement of the car. This horizontal movement of the elevator car is caused due to a guiding member attached in vibration proof relationship to the car to guide the latter along an associated guide rail.
Accordingly it is an object of the present invention to provide a new and improved position sensor device for use with an elevator car which senses the position of the elevator car traveling along either end portion of its path of movement in an error free manner.